org.apache.oozie.util.WritableUtils Maven / Gradle / Ivy
/**
* Copyright (c) 2010 Yahoo! Inc. All rights reserved.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License. See accompanying LICENSE file.
*/
package org.apache.oozie.util;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.util.ReflectionUtils;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.DataOutput;
import java.io.DataInput;
/**
* Utility class to write/read Hadoop writables to/from a byte array.
*/
public class WritableUtils {
/**
* Write a writable to a byte array.
*
* @param writable writable to write.
* @return array containing the serialized writable.
*/
public static byte[] toByteArray(Writable writable) {
try {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
DataOutputStream daos = new DataOutputStream(baos);
writable.write(daos);
daos.close();
return baos.toByteArray();
}
catch (IOException ex) {
throw new RuntimeException(ex);
}
}
/**
* Read a writable from a byte array.
*
* @param array byte array with the serialized writable.
* @param clazz writable class.
* @return writable deserialized from the byte array.
*/
@SuppressWarnings("unchecked")
public static T fromByteArray(byte[] array, Class clazz) {
try {
T o = (T) ReflectionUtils.newInstance(clazz, null);
o.readFields(new DataInputStream(new ByteArrayInputStream(array)));
return o;
}
catch (IOException ex) {
throw new RuntimeException(ex);
}
}
private static final String NULL = "||";
/**
* Write a string to a data output supporting null values. It uses the '||' token to represent
* null.
*
* @param dataOutput data output.
* @param str string to write.
* @throws IOException thrown if the string could not be written.
*/
public static void writeStr(DataOutput dataOutput, String str) throws IOException {
str = (str != null) ? str : NULL;
dataOutput.writeUTF(str);
}
/**
* Read a string from a data input supporting null values. It uses the '||' token to represent
* null.
*
* @param dataInput data input.
* @return read string, null if the '||' token was read.
* @throws IOException thrown if the string could not be read.
*/
public static String readStr(DataInput dataInput) throws IOException {
String str = dataInput.readUTF();
return (str.equals(NULL)) ? null : str;
}
}